DIFFERENCE OF GEOMETRIC MEAN

DIFFERENCE OF GEOMETRIC MEAN (LET)

Let Subcommand

Compute the difference between the geometric means for two response variables.

The geometric mean is defined as:
\( \mbox{XGM} = (\prod_{i=1}^{n}{X_i})^{1/n} \)

For the differeence of geometric means, the geometric mean is computed for each of two samples then their difference is taken.

LET <par> = DIFFERENCE OF GEOMETRIC MEAN <y1> <y2>                         <SUBSET/EXCEPT/FOR qualification>
where <y1> is the first response variable;
            <y2> is the first response variable;
            <par> is a parameter where the computed difference of the geometric means is stored;
and where the <SUBSET/EXCEPT/FOR qualification> is optional.

LET A = DIFFERENCE OF GEOMETRIC MEAN Y1 Y2
LET A = DIFFERENCE OF GEOMETRIC MEAN Y1 Y2 SUBSET X > 1

Dataplot statistics can be used in a number of commands. For details, enter
HELP STATISTICS

None

None

GEOMETRIC MEAN	= Compute the geometric mean.
DIFFERENCE OF MEAN	= Compute the difference of means.
DIFFERENCE OF HARMONIC MEAN	= Compute the difference of harmonic means.
DIFFERENCE OF MEDIAN	= Compute the difference of medians.
DIFFERENCE OF TRIMMED MEAN	= Compute the difference of trimmed means.
DIFFERENCE OF MIDMEAN	= Compute the difference of midmeans.
DIFFERENCE OF BIWEIGHT LOCATION	= Compute the difference of biweight locations.
STATISTICS PLOT	= Generate a statistic versus subset plot.
BOOTSTRAP PLOT	= Generate a bootstrap plot.
TABULATE	= Perform a tabulation for a specified statistic.

Data Analysis

2003/03

SKIP 25 
READ IRIS.DAT Y1 TO Y4 X 
. 
LET A = DIFFERENCE OF GEOMETRIC MEAN Y1 Y2 
TABULATE DIFFERENCE OF GEOMETRIC MEAN Y1 Y2 X 
. 
XTIC OFFSET 0.2 0.2
X1LABEL GROUP ID
Y1LABEL DIFFERENCE OF GEOMETRIC MEANS
CHAR X 
LINE BLANK 
DIFFERENCE OF GEOMETRIC MEAN PLOT Y1 Y2 X 
CHAR X ALL 
LINE BLANK ALL 
BOOTSTRAP DIFFERENCE OF GEOMETRIC MEAN PLOT Y1 Y2 X  
    

Dataplot generates the following output.

       **************************************************
       **  LET A = DIFFERENCE OF GEOMETRIC MEAN Y1 Y2  **
       **************************************************
  
  
 THE COMPUTED VALUE OF THE CONSTANT A             =  0.27591226E+01
  
  
       *****************************************************
       **  TABULATE DIFFERENCE OF GEOMETRIC MEAN Y1 Y2 X  **
       *****************************************************
  
  
                 *    Y1       AND Y2
     X           *    DIFFERENCE OF GEOMETRIC MEANS
 **********************************************
     1.00000     *     1.58676
     2.00000     *     3.16211
     3.00000     *     3.60078
  
       GROUP-ID AND STATISTIC WRITTEN TO FILE DPST1F.DAT